A processing technology of rare earth water washing solution

Abstract

The application discloses a treatment process of rare earth water washing liquid, comprising the following steps: obtaining previous water washing liquid to obtain high-concentration lye, and obtaining subsequent residual water washing liquid to obtain low-concentration lye; adding a calcium source into the high-concentration lye and stirring until no precipitation is generated, so as to obtain a high-alkali solution with a preset hydroxyl ion concentration; adding ammonia distillation wastewater into the low-concentration lye, and performing overflow on supernatant; adding the solution after overflow into the ammonia distillation wastewater again, and performing overflow on supernatant, the step is repeated for multiple times until no precipitation is generated, and the finally obtained solution is treated by adding acid or concentration. The application can treat the ammonia distillation wastewater and the water washing liquid mutually, obviously reduces the wastewater treatment cost, and improves the economy.

Description

Technical Field

[0001] This invention belongs to the field of rare earth mineral production and processing technology, and relates to a treatment process for rare earth washing solution. Background Technology

[0002] The extraction process of rare earth ore generates various types of wastewater, such as ammonia stripping wastewater and washing liquid. Ammonia stripping wastewater contains a large amount of ammonium and calcium ions, while washing liquid is obtained by washing phosphorus and fluoride after treating rare earth waste residue with alkali roasting. Currently, treating the ammonia stripping wastewater and washing liquid separately using conventional methods is costly and uneconomical. Summary of the Invention

[0003] The purpose of this invention is to provide a rare earth washing solution treatment process that can treat ammonia stripping wastewater and washing solution together, significantly reducing wastewater treatment costs and improving economic efficiency.

[0004] The technical solution adopted in this invention is as follows:

[0005] A process for treating rare earth washing solutions includes the following steps:

[0006] Obtain the water solution from the first few washes to obtain a high concentration of alkaline water, and obtain the remaining water solution from the subsequent washes to obtain a low concentration of alkaline water.

[0007] Add a calcium source to the high-concentration alkaline water and stir until no more precipitate is produced to obtain a high-alkaline solution with a preset hydroxide concentration.

[0008] Add ammonia-removed wastewater to the low-concentration alkaline water and overflow the supernatant;

[0009] The overflowed solution is added back to the ammonia stripping wastewater and the supernatant is overflowed. This step is repeated multiple times until no more precipitate is produced. The final solution is then treated with acid or concentrated.

[0010] The ammonia-steaming wastewater is wastewater generated from the production and processing of rare earth minerals. The ammonia-steaming wastewater contains calcium ions and its aqueous solution is alkaline.

[0011] Furthermore, the calcium source includes quicklime and / or the ammonia-evaporized wastewater.

[0012] Furthermore, the high-concentration alkaline water is the first or second wash solution.

[0013] Furthermore, the acid used in the acid treatment is hydrochloric acid.

[0014] Furthermore, the concentration process includes: heating and evaporating the final obtained solution to concentrate it so that the obtained solution is within the preset hydroxide concentration range.

[0015] Furthermore, the preset hydroxide concentration is 4-6 mol / L.

[0016] Furthermore, the preset hydroxide concentration is 5 ± 0.2 mol / L.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] In the wastewater treatment process of this invention, the washing liquid generated from multiple washing processes in the alkali roasting step is divided into two categories. One category is the high-concentration alkaline water obtained from the initial multiple washing processes, which has a high hydroxide concentration. The other category is the low-concentration alkaline water obtained from subsequent multiple washing processes, which has a lower hydroxide concentration. The high-concentration alkaline water, when treated with a calcium source, can remove phosphorus through calcium phosphate precipitation and fluoride through calcium fluoride precipitation. The resulting high-concentration alkaline solution has a high hydroxide concentration and can be directly sold. The low-concentration alkaline water, after being treated with ammonia-containing wastewater and subjected to multiple overflow treatments, not only treats the ammonia-containing wastewater generated during rare earth ore production and processing, but also removes phosphorus and fluoride through calcium phosphate and calcium fluoride precipitation. The final solution has a low hydroxide concentration and can be treated with acid or concentrated for sale. This wastewater treatment process of the present invention can mutually treat ammonia-containing wastewater and washing liquid, significantly reducing wastewater treatment costs and improving economic efficiency. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein:

[0020] Figure 1 is a flow chart of the low-concentration alkaline water treatment process in the wastewater treatment process of the present invention;

[0021] Figure 2 is a flow chart of the high-concentration alkaline water treatment process in the wastewater treatment process of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0024] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0025] As described in the background section, various types of wastewater are generated during the rare earth ore extraction process, such as ammonia stripping wastewater and washing liquid. Ammonia stripping wastewater contains large amounts of ammonium and calcium ions, while washing liquid is obtained by washing rare earth waste residue after alkaline roasting to remove phosphorus and fluoride. Currently, treating the ammonia stripping wastewater and washing liquid separately using conventional methods is costly and uneconomical.

[0026] Based on this, the inventors created a rare earth washing liquid treatment process as described in this application to solve the above-mentioned technical problems.

[0027] The features and performance of the present invention will be further described in detail below with reference to embodiments. Example

[0028] Please refer to Figures 1 and 2. A treatment process for a rare earth washing solution includes the following steps:

[0029] S1. Obtain the water solution from the first few washes to obtain a high-concentration alkaline solution, and obtain the remaining water solution from the subsequent washes to obtain a low-concentration alkaline solution. For example, the high-concentration alkaline solution can be the water solution from the first one or the first two washes, while the low-concentration alkaline solution is the water solution produced by the subsequent washes.

[0030] S2. Add a calcium source to the high-concentration alkaline water and stir until no more precipitate is formed, thus obtaining a high-alkaline solution with a preset hydroxide concentration. For example, the calcium source may include quicklime and / or ammonia stripping wastewater. Both quicklime and ammonia stripping wastewater contain calcium ions and their aqueous solutions are alkaline. Ammonia stripping wastewater is wastewater generated from the production and processing of rare earth minerals, while quicklime is also inexpensive, making the treatment of high-concentration alkaline water economically viable.

[0031] S3. Add ammonia-removed wastewater to the low-concentration alkaline water and overflow the supernatant;

[0032] S4. Add the overflowed solution back to the ammonia-removing wastewater and overflow the supernatant. Repeat this step multiple times until no more precipitate is formed. Treat the final solution with acid (e.g., hydrochloric acid) or concentrate it. For example, concentration may include heating and evaporating the final solution to concentrate it to a predetermined hydroxide concentration range. Concentration is simple and can be sold together with the high-alkalinity solution obtained from treating high-concentration alkaline water. For example, the predetermined hydroxide concentration is 4-6 mol / L (e.g., 4.2 mol / L, 4.6 mol / L, 5.0 mol / L, 5.4 mol / L, 5.8 mol / L).

[0033] Preferably, the preset hydroxide concentration can be 5 ± 0.2 mol / L.

[0034] In the wastewater treatment process of this invention, the washing liquid generated from multiple washing processes in the alkali roasting step is divided into two categories. One category is the high-concentration alkaline water obtained from the initial multiple washing processes, which has a high hydroxide concentration. The other category is the low-concentration alkaline water obtained from subsequent multiple washing processes, which has a lower hydroxide concentration. The high-concentration alkaline water, when treated with a calcium source, can remove phosphorus through calcium phosphate precipitation and fluoride through calcium fluoride precipitation. The resulting high-concentration alkaline solution has a high hydroxide concentration and can be directly sold. The low-concentration alkaline water, after being treated with ammonia-containing wastewater and subjected to multiple overflow treatments, not only treats the ammonia-containing wastewater generated during rare earth ore production and processing, but also removes phosphorus and fluoride through calcium phosphate and calcium fluoride precipitation. The final solution has a low hydroxide concentration and can be treated with acid or concentrated for sale. This wastewater treatment process of the present invention can mutually treat ammonia-containing wastewater and washing liquid, significantly reducing wastewater treatment costs and improving economic efficiency.

[0035] The specific experimental data are shown in Table 1 below:

[0036]

[0037] As can be seen from the table, the present invention can make full use of the wastewater generated from rare earth ore processing to treat low-concentration alkaline water and high-concentration alkaline water with high efficiency, effectively realize waste utilization, and is very economical.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A treatment process for rare earth washing solution, characterized in that, Includes the following steps: Obtain the water solution from the first few washes to obtain a high concentration of alkaline water, and obtain the remaining water solution from the subsequent washes to obtain a low concentration of alkaline water. Add a calcium source to the high-concentration alkaline water and stir until no more precipitate is produced to obtain a high-alkaline solution with a preset hydroxide concentration. Add ammonia-removed wastewater to the low-concentration alkaline water and overflow the supernatant; The overflowed solution is added back to the ammonia stripping wastewater and the supernatant is overflowed. This step is repeated multiple times until no more precipitate is produced. The final solution is then treated with acid or concentrated. The ammonia-steaming wastewater is wastewater generated from the production and processing of rare earth minerals. The ammonia-steaming wastewater contains calcium ions and its aqueous solution is alkaline.

2. The treatment process for a rare earth washing solution according to claim 1, characterized in that, The calcium source includes quicklime and / or the ammonia-evaporized wastewater.

3. The treatment process for a rare earth washing solution according to claim 1, characterized in that, The high-concentration alkaline water is the first or second wash solution.

4. The treatment process for a rare earth washing solution according to claim 1, characterized in that, The acid used in the acid treatment is hydrochloric acid.

5. The treatment process for a rare earth washing solution according to any one of claims 1-4, characterized in that, The concentration process includes heating and evaporating the final solution to concentrate it, so that the resulting solution is within the preset hydroxide concentration range.

6. The treatment process for a rare earth washing solution according to claim 5, characterized in that, The preset hydroxide concentration is 4-6 mol / L.

7. The treatment process for a rare earth washing solution according to claim 1, characterized in that, The preset hydroxide concentration is 5 ± 0.2 mol / L.

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